This invention relates to accelerometer leveling, and in particular accelerometer leveling in an actively controlled vehicle suspension system.
Many conventional vehicles such as automobiles include passive suspension systems which include a system of springs, shock absorbers and linkages which connect the vehicles to their wheels. The suspension system typically ensures that the vehicle can adequately and safely drive over a wide range of road conditions (i.e., can handle well) while also ensuring that the passengers of the vehicle are comfortable (i.e., the ride isn't overly rough or noisy).
In general, as the suspension is tuned to increase passenger comfort, the handling of the vehicle is sacrificed. Conversely, as the suspension is tuned to increase the handling ability of the vehicle, the passenger comfort is sacrificed. Thus, designing vehicle suspensions can be seen as a tradeoff between passenger comfort and handling ability. However, even with the most finely tuned suspensions, when a vehicle accelerates, decelerates, or turns, the chassis of the automobile tends to pitch, heave, and/or roll. Such changes in the orientation of the vehicle's chassis can cause decreased passenger comfort and decreased handling performance.
One solution to the shortcomings of passive vehicle suspension systems is to use active vehicle suspension systems. Active vehicle suspension systems sense motion of the vehicle's chassis (e.g., using accelerometers and other inertial sensors) and control actuators at each of the wheels of the vehicle based on the sensed motion. The actuators are controlled to mitigate undesirable pitch, roll, and heave of the vehicle chassis while at the same time isolating the chassis from road roughness, thereby improving passenger comfort and handling performance.